Trucks are typically backed into or in close proximity to a loading dock or other opening in the building to facilitate loading and unloading of the vehicle. Since the width of the dock opening is typically larger than truck width so that vehicles of different sizes can be readily serviced, a gap is formed between the loading dock walls and the vehicle which exposes the interior of the building to the outside weather and permits air to flow into or out of the building. Attempts to seal the interior of the building from the outside environment have included loading dock shelters which utilize fabric or sheet material to form walls or curtains between the opening and the truck and loading dock seals which utilize resilient, compressible pad members, generally disposed at the lateral and top edges of the opening, to sealably engage the walls or rear edges of the truck.
Unfortunately, many typical loading dock seals and shelters have several disadvantages. Since the dock seals must be disposed so that they overlap or extend into the truck's doorway to ensure that the rear edges of the truck engage the compressible pad members, they have reduced the size of the passageway, limiting access into the truck and generally inhibiting loading and unloading of the truck. The compressible pads also require the truck to exert considerable force on the pad in order to obtain the proper sealing engagement, increasing abrasion and wear on the seal and curtain materials, particularly where the rear corners and edges of the truck rub against the material. Attempts to protect against such abrasion and wear including, for example, reinforcing the materials with several layers have been largely unsatisfactory because, although they increase or prolong the wear resistance of the material, they have the inherent disadvantage of increasing cost. Since many loading docks have non-horizontal, angled or tilted driveway grades, many loading dock shelters must be individually manufactured in order to accommodate such grades and maintain the proper perpendicular orientation between the truck walls and the seals. This increases manufacturing and installation costs. Although it is desirable to seal the truck and opening to prevent the escape of heated or air conditioned air during inclement weather, it is undesirable to do so during mild weather. Unfortunately, the pads and the frame of the shelter, typically disposed along the periphery of the opening, can not be removed or adjusted to unseal the opening.